1. Field of the Invention
The present invention relates to a circuit arrangement for limiting and regulating the collector current of a control transistor of a switching network component employing an integrated current and voltage regulator component which includes a pulse width modulator, a reference voltage source, an operational amplifier for current regulation, an operational amplifier for voltage regulation, a disconnect device and two dual outputs.
2. Description of the Prior Art
In switching network components, the protection of the switching transistors from excess current is of the greatest importance. Regulation is effected by known integrated regulating modules which permit a combined voltage and current regulation with the aid of operational amplifiers and a pulse phase modulator. This regulating module is normally operated in such a manner that with the aid of a current transformer, the operational amplifier provided for current regulation is used to detect the measured values of slow current changes. For rapid current changes or current peaks of very steep gradient, it is normal to use the input of a disconnect device, likewise contained in the integrated regulating module, or else the operational amplifier for voltage regulation. Suddenly-occurring current peaks do, in fact, result in a simultaneous blockage of the outputs, but the reverse-flowing current permits an immediate reconnection which can result in considerable oscillation processes in the collector circuit. In this case, a resistor, capacitor, diode (RCD) protective circuit of the switching transistor loses efficiency. The switching process is largely unchecked and can lead to the destruction of the switching transistor. In the case of slow current changes, the above-described processes fundamentally occur at the time of the transition from voltage regulation to current regulation. However, both forms of current detection are fundamentally required, as is an additional starting circuit relating to the increase in the pulse width of the switching transistor drive.